A preliminary report on the toxicology of zircon (Harding, 1948) gave some details of the properties and uses of this substance and suggested that it was extremely inert within the animal body. At the time of the publication of this preliminary report an experiment was almost completed during which rats were exposed to afairly high concentration (725,000 particles per cc. of air) of zircon dust...

The Bouse Formation in the lower Colorado River trough holds an important record of the onset of the modern drainage patterns in the southwestern United States. It comprises calcareous and clastic infi ll deposited during fl ooding of several basins, including the Bristol and Blythe subbasins of Lake Bouse. An intercalated ash bed, which is key to constraining its depositional age, is exposed i...

This paper presents a new approach to quantify sediment mixing based on the mixing of U–Pb zircon age distributions within sediment. Two statistical techniques are presented to determine the proportion in which two known age distributions combine to create a known mixed age distribution. These techniques are then used to determine relative erosion rates between adjacent drainage basins above an...

Cretaceous represents one of the hottest greenhouse periods in the Earth's history, but some recent studies suggest that small ice caps might be present in non-polar regions during certain periods in the Early Cretaceous. Here we report extremely negative δ(18)O values of -18.12‰ to -13.19‰ for early Aptian hydrothermal zircon from an A-type granite at Baerzhe in northeastern China. Given that ...

New SHRIMP and TIMS zircon ages, Ar=Ar ages, and eclogite locations contribute significantly to our understanding of the ultrahigh-pressure Dabie Shan. (1) The geographic extent of the Yangtze craton that was subducted to ultrahigh pressure extends to the northern edge of the Dabie Shan. (2) The northern half of the Dabie Shan is a magmatic complex, intruded over a 10-Myr interval between 137 a...

Earlier *-ray studies of thorite have indicated that it is metamict (Vegard, 1916) or have led to cell dimensions (Boidyrev, 1938) that seem out of line with those of related materials. Single crystal r-ray difiraction patterns have been obtained from unaltered uranothorite from Gillespie's Beach, South Westland, New Zealand. Rotation patterns on the a and c axes are very similar to zircon patt...

The titanium concentrations of 484 zircons with U-Pb ages of *1 Ma to 4.4 Ga were measured by ion microprobe. Samples come from 45 different igneous rocks (365 zircons), as well as zircon megacrysts (84) from kimberlite, Early Archean detrital zircons (32), and zircon reference materials (3). Samples were chosen to represent a large range of igneous rock compositions. Most of the zircons contai...

Detrital zircon U-Pb ages for 30 Late Jurassic and Cretaceous sandstones from the Eastern Province of eastern New Zealand, combined with previously-published geochronological and palaeontological data, constrain the time of deposition in the Pahau and Waioeka terranes of the Cretaceous accretionary margin of Zealandia, and their adjacent cover strata. The zircon age patterns also constrain poss...

Introduction: Apatite is one of the minerals that is rarely utilized in U-Pb geochronology, compared to some other U-rich accessory phases. Relatively low U concentration, commonly high proportion of common Pb and low closure temperature of U-Pb system of apatite inhibit its application as geochronological tool when other minerals such as zircon are widely available. However, zircon appear to b...